1. Field
Embodiments of the present invention relate to fluid-filled lenses and in particular to variable fluid-filled lenses.
2. Background Art
Basic fluid lenses have been known since about 1958, as described in U.S. Pat. No. 2,836,101, incorporated herein by reference in its entirety. More recent examples may be found in “Dynamically Reconfigurable Fluid Core Fluid Cladding Lens in a Microfluidic Channel” by Tang et al., Lab Chip, 2008, vol. 8, p. 395, and in WIPO publication WO2008/063442, each of which is incorporated herein by reference in its entirety. These applications of fluid lenses are directed towards photonics, digital phone and camera technology and microelectronics.
Fluid lenses have also been proposed for ophthalmic applications (see, e.g., U.S. Pat. No. 7,085,065, which is incorporated herein by reference in its entirety). In all cases, the advantages of fluid lenses including a wide dynamic range, ability to provide adaptive correction, robustness and low cost have to be balanced against limitations in aperture size, tendency to leak and consistency in performance. The '065 patent, for example, has disclosed several improvements and embodiments directed towards effective containment of the fluid in the fluid lens to be used in ophthalmic applications, although not limited to them (see, e.g., U.S. Pat. No. 6,618,208, which is incorporated by reference in its entirety). Power adjustment in fluid lenses has been effected by injecting additional fluid into a lens cavity, by electrowetting, application of ultrasonic impulse, and by utilizing swelling forces in a cross-linked polymer upon introduction of a swelling agent such as water.
In all cases, there are several key limitations in fluid lens technology that need to be overcome to optimize the commercial appeal of this technology. For example, the thickness of fluid lenses is generally greater than conventional lenses of the same power and diameter. Additionally, it is not currently possible to provide a variation of spherical power as well as astigmatism across the lens optic using fluid lens technology. Nor have fluid lenses been manufactured in any desired shape other than a round shape because of complications introduced in non-uniform expansion of non-round fluid lenses. It is therefore desirable to provide solutions to these limitations so commercialization becomes feasible.